This invention relates to electrostatographic xerographic type reproduction machines, and more particularly, to an improved control system for such machines.
The advent of higher speed and more complex copiers and reproduction machines has brought with it a corresponding increase in the complexity in the machine control wiring and logic. While this complexity manifests itself in many ways, perhaps the most onerous involves in inflexibility of the typical control logic/wiring systems. For as can be appreciated, simple unsophisticated machines with relatively simple control logic and wiring can be altered and modified easily to incorporate changes, retrofits, and the like. Servicing and repair of the control logic is also fairly simple. On the other hand, some modern high speed machines, which often include sorters, a document handler, choice of copy size, multiple paper trays, jam protection and the like have extremely complex logic systems making even the most minor changes and improvements in the control logic difficult, expensive and time consuming. And servicing or repairing the machine control logic may similarly entail substantial difficulty, time and expense.
To mitigate problems of the type alluded to, a programmable controller may be used, enabling changes and improvements in the machine operation to be made through the expediency of reprogramming the controller. However, the control data which operates the machine and which is stored in the controller memory pending use, must be transferred to the various machine components at the proper time and in the correct sequence without unduly interfering with or intruding unnecessarily upon the other essential functions and operations of the controller.
It is therefore a principal object of the present invention to provide a new and improved control system for electrostatic type reproduction machines.
It is a further object of the present invention to provide a method, in a control system for copiers, to provide increased time for carrying out overlong control sequences.
It is an object of the present invention to provide, in a copier control system comprised of both real time based background control functions and synchronized foreground control functions interposed on the background control functions periodically, an arrangement for accommodating overlong foreground control functions by spooling at least a part of the overlong foreground control function in with the background control functions.
It is an object of the present invention to provide a system for controlling reproduction machines wherein overlong control functions are recognized and shifted from a synchronous timing constraint to a real timimg constraint.
This invention relates to the method of operating an electrostatic type copy reproducing machine to produce copies in accordance with copy run instructions, the machine including relatively permanent background operating routines for operating the machine and foreground routines, at least a portion of the foreground routines reflecting the copy run instructions, the steps which comprise: actuating the background routines in preset timed order to render the machine operable; interrupting the background routines periodically and in synchronism with the machine for a preset interval to carry out a foreground routine; shifting at least the portion of a foreground routine that cannot be completed in the preset interval into the background routine; and completing any of the overlong foreground routine on return to the background routine.